聲明：以下內(nèi)容只是用來作為個人學(xué)習(xí)、熟悉swift語言開發(fā)或者今后查閱資料使用见秽，也會隨著語言的不不斷更新而不斷的進(jìn)行更新發(fā)布....

UILabel用來在界面上顯示一行或多行文本踱讨，下面就介紹常見屬性與基本用法。

1、UILabel創(chuàng)建####

//創(chuàng)建的時候設(shè)置frame
let testLable=UILabel(frame:CGRect(x:20,y:100,width:self.view.frame.size.width - 40,height:400))
        
//先創(chuàng)建铡羡，在進(jìn)行位置大小設(shè)定，和上面的作用一樣的      
let Label = UILabel()
Label.frame = CGRect(x:20,y:100,width:self.view.frame.size.width - 40,height:400)

//添加       
self.view.addSubview(Label);

2意鲸、UILabel常見屬性設(shè)置####

//顯示文本內(nèi)容
testLable.text = "nice to meet you!"

//背景顏色
testLable.backgroundColor = UIColor.green

//文字顏色
testLable.textColor = UIColor.white

//文字對齊方式
testLable.textAlignment = NSTextAlignment.left

其中文字對齊方式有以幾種：
 /* Values for NSTextAlignment */
 @available(iOS 6.0, *)
 public enum NSTextAlignment : Int {
 
 
 case left // Visually left aligned
 
 
 case center // Visually centered
 
 case right // Visually right aligned
 
 /* !TARGET_OS_IPHONE */
 // Visually right aligned
 // Visually centered
 
 case justified // Fully-justified. The last line in a paragraph is natural-aligned.
 
 case natural // Indicates the default alignment for script
 }


//陰影顏色
testLable.shadowColor = UIColor.black

//陰影偏移位置
testLable.shadowOffset = CGSize(width:-5,height:5)

//根據(jù)視圖寬度自動調(diào)整文字大小
testLable.adjustsFontSizeToFitWidth = true

//高亮?xí)r候的文字顏色
testLable.highlightedTextColor = UIColor.cyan
        
//設(shè)置圓角
testLable.layer.cornerRadius = 20
testLable.layer.masksToBounds = true

//邊框的寬度和顏色
testLable.layer.borderColor = UIColor.green.cgColor
testLable.layer.borderWidth = 2
     
//文字類型/大小   
testLable.font = UIFont.boldSystemFont(ofSize: 20) //加粗類型
testLable.font = UIFont.systemFont(ofSize: 20)//文字大小
testLable.font = UIFont.italicSystemFont(ofSize: 20)//斜體類型

//大小和文字一起設(shè)置
testLable.font = UIFont(name:"您好",size:50)

//顯示樣式
testLable.lineBreakMode = NSLineBreakMode.byCharWrapping

// NSParagraphStyle
@available(iOS 6.0, *)
public enum NSLineBreakMode : Int {

case byWordWrapping // Wrap at word boundaries, default

case byCharWrapping // Wrap at character boundaries

case byClipping // Simply clip

case byTruncatingHead // Truncate at head of line: "...wxyz"

case byTruncatingTail // Truncate at tail of line: "abcd..."

case byTruncatingMiddle // Truncate middle of line:  "ab...yz"
}

//多行顯示
label.numberOfLines = 2//最多顯示2行
label.numberOfLines = 0// 默認(rèn)沒有行數(shù)顯示
label.numberOfLines = 1//只能顯示一行

3烦周、富文本設(shè)置####

//創(chuàng)建對象
let attributeString = NSMutableAttributedString(string:"Welcome to Swift! Welcome to Swift! Welcome to Swift! Welcome to Swift!")
//設(shè)置字體大小/字體類型
attributeString.addAttribute(NSFontAttributeName, value: UIFont(name: "HelveticaNeue-Bold", size: 16)!, range: NSMakeRange(0, 6))
//設(shè)置背景顏色           
attributeString.addAttribute(NSForegroundColorAttributeName, value: UIColor.red, range: NSMakeRange(0, 3))          
//設(shè)置文檔背景色     attributeString.addAttribute(NSBackgroundColorDocumentAttribute, value: UIColor.lightGray, range: NSMakeRange(10, 10))
//設(shè)置下劃線
attributeString.addAttribute(NSUnderlineStyleAttributeName, value:NSUnderlineStyle.StyleSingle.rawValue, range: NSMakeRange(5,12))
        
testLable.attributedText = attributeString;

4、文本高度計算####

關(guān)于lable顯示文本的高度計算也是老生常談怎顾，下面就簡單的舉個例子以extension為例：

extension NSString {
    func textSizeWithFont(font: UIFont, constrainedToSize size:CGSize) -> CGSize {
        var textSize:CGSize!
        if CGSizeEqualToSize(size, CGSizeZero) {
            let attributes = NSDictionary(object: font, forKey: NSFontAttributeName)
            textSize = self.sizeWithAttributes(attributes)
        } else {
            let option = NSStringDrawingOptions.UsesLineFragmentOrigin
            let attributes = NSDictionary(object: font, forKey: NSFontAttributeName)
            let stringRect = self.boundingRectWithSize(size, options: option, attributes: attributes, context: nil)
            textSize = stringRect.size
        }
        return textSize
    }
}